1. (

• complex_number ,
• complex_quantity ,
• imaginary_number ,
• imaginary

) (mathematics) a number of the form a+bi where a and b are real numbers and i is the square root of -1 ;

1. (

• fanciful ,
• imaginary ,
• notional

) not based on fact; existing only in the imagination; "the falsehood about some fanciful secret treaties"- F.D.Roosevelt; "a small child's imaginary friends"; "to create a notional world for oneself" ;